Art of photo-engraving.



H. J. VAN VALKENBURG ART OF PHOTO ENGRAVING.

APPLICATION FILED JUNE 9, 1915.

Patented July 11, 1916.

' INVENTOR Harry J I n 1611M my 6 By WITNESSES.

HARRY J. VAN VALKENBUBG, OF ROCHESTER, NEW YORK.

ART OF PHOTO-ENGBA'VING.

Specification of Letters Intent.

Patented July 11, 1916.

Application filed June 9, 1915. Serial No. 33,167.

To all whom it 111 (13 concern:

Be it known that I, HARRY J. VAN VALK- ENBURG, a citizen of the UnitedStates, residing at Rochester, in the county of Monroe and State of NewYork, have invented a new and useful Improvement in the Art ofPhoto-Engraving, of which the following is a specification.

, My invention relates more particularly to hoto-engraving in half-tone,and the obect thereof is, by means of photography, to drop out oreliminate all half-tone dots from any predetermined portions on anegative made through any half-tone screen whether ruled or grained.

Heretofore, in order to have high light or pure white background, freefrom all half-tone dots, it has been necessary after the reproductionhad' been transferred to the zinc or copper plate to follow the outlineof the photograph with a ,sharp tool called a graver in order to removethe half-tone dots adjacent thereto before usin mainder of thebackground are routed out. This first named operation not only requiresa skilled hand but is slow and consequently expensive, while in thepractice of my invention the necessity of such operation is entirelyobviated.

The method and means I employ in eliminating half-tone dots from anypredetermined portions on a negative, as around the outline of. theobject photographed, areillustrated, diagrammatically, in theaccompanying drawings, in which,

Figure 1 shows a face view of a copy (photograph, drawing, print,lithograph or other subject) of which a half-tone negative is to bemade; Fig. 2, a view of the copy similar to Fig. 1 but showing a sheetof thin colorless transparent material secured to the face thereof onwhich is made a tracing, in white opaque pigment, over that portion ofthe copy from which all half-tone dots are to be eliminated on thenegative; Fig. 3, a side view of the parts seen in Fig. 2; Fig. 4, aView showing a portion of a sheet of colored transparent material thatmay be used instead of that shown in Fig. 2; Fig. 5, a view similar toFig. 2 but showing a backing sheet disposed between the transparentmaterial and the copy, such sheet being of a color having non-actinicvalue; Fig. 6, a side View of the parts seen in Fig. 5 placed in a copyholding frame with the back and glass front of such frame shown invertical the inst-rument by means of which the ots in the re section;Fig. 7, the appearance of a negative if developed after an exposure hadbeen made with the backing sheet in the position shown in Fig. 5; Fig.8, a face view of a half-tone negative on which a photograph of the copyhas been made; Fig. 9, a face view of a half-tone plate made from thenegative seen in Fig. 8; and Fig. 10, a view similar to Fig. 2 butshowing a reversal of theprocess, as will be explained.

Similar reference characters refer to similar parts throughout theseveral views.

In Fig. 1 the numeral 1 represents the copy to .be photographed which ofitself may be a photograph, print, drawing, lithograph or othensubject,and at 2 is seen the background from' which on the finished print allhalf-tone dots are to be eliminated.

A sheet of thin colorless transparent material 3, preferably celluloidabout 3/1000 of an inch thick and of sufficient area to cover the entiresurface to be photographed, 1s placed over the copy 1 and attachedfirmly thereto at two or more points by means of a suitable adhesive or,if desired, may be covered over its entire surface with a transparentcement in order to be held in close contact with the copy. Upon thistransparent material a tracking 4 is then made in opaque pigment of highactinic value, as white, of that portion of the copy from which all dotsare to be eliminated by photography from the half-tone. That portionof'the negative on which no dots are to appear, as illustrated in thedrawings, is a margin following the outline of the object 5 on the copy1.

After the tracing 4 has been made the sheet 3 is raised from the copy 1to permit the insertion therebetween of a backing 6 of suitablematerial, as celluloid, paper or other substance of a color having anon-actinic value, but is held fast to the copy at two or more points inorder that the tracing may again be brought into registration with theobject 5. The material 6 indicated in Figs. 5 and 6 of the drawings, andwhich I prefer to use, is red celluloid. All three, copy, tracing andbacking are next placed in the usual copy holding frame 7 having ahinged glass front 8, sufficient pressure being) brought to bear to holdsuch three mem ers in perfect contact wit-h each other, and in orderthat the frame may be opened to later remove the backing 6 withoutdisturbing the position of the copy 1 such copy is secured by tacks, notshown, to the back of the frame 7. A photographic exposure This exposuremay be made either with or without the use of a half-tone screen, but ifmade through the screen sufiicient exposure must be given together withaproper relative lens aperture and screen separation to insure thecomplete closing up of. all halftone dot formation. If the'negative weredeveloped at this time in the process the result would be as shown inFig. 7 in which 9 represents the photograph of the tracing 4, theremainder of the negative 10 being clear glass.

After such first exposure is made, which may be almost instantaneous orvar up to forty-five seconds or more, the hacking member 6 is removed onopening the glass front 8 of the copy holder and which is thereafteragain closed to hold the transparent sheet 3 and copyl in contact witheach other and with the tracing 4 in perfect registration with theobject 5. The regular half-tone exposure of the copy 1 is then made andthe developed negative 11 would 7 appear as in Fig. 8 with the object 5and background 2 shown in half-tone dots, but with the margin 9 formedaround the outline of the object showing black on the negative.

A half-tone plate made from the negative 11 would be as indicated at 12in Fig. 9, and it will readily be seen that with the margin around theoutline of the object photographed free from all half-tone dots the useof the graver tool, for the purpose above referred to, is dispensed withand that the remainder of the background may be cleared of half-tonedots by use of the routing instrument only.

If desired, the transparent sheet 3 having the tracing 4 thereon may beremoved with the backing 6 from the copy 1 before the second exposure orhalf-tone negative, proper, is made; and it will, therefore, be readilyunderstood that, if a tracing 4 in pigment of high actinic value is madeon a sheet of transparent material, as indicated in Fig. 4 at 13, of acolor having non-actinic value, the backing sheet 6 need not be used.

The entire process of making the half- 7 tone negative'may be reversedby using,

instead of a pigment of high actinic value and making a tracing of thatportion of the copy from which all half-tone dots are to be eliminated,apigment of non-actinic value and making a tracing of that portion of thecopy from which such dots are not to be eliminated in the half-tonenegative, a tracing of this kind being shown at 14 in Fig.

10 as made on a sheet of transparent material 3 similar to that shown inFig. 2; and

when this reverse method is followed an opaque backing sheet 15 havinghigh actinic value is used, and both the backing and the sheet 3 onwhich the tracing is made must be removed from the copy before thesecond exposure of the negative is made.

It is believed that, from the foregoing description, the method of andmeans used in practising my invention, as well as the purpose thereof,are sufliciently understood to call for no further explanation herein.

What I claim is:

1. The improvement in the art of photoengraving which consists ineliminating half-tone dots from predetermined portions of a half-tonenegative by covering the copy to be photographed with a trans arentmaterial including a layer of a co or having non-actinic value, tracingon said material over portions of said copy from which all half-tonedots are to be eliminated from the negative with a pigment having highactinic value, photographing said tracing on a sensitized plate, removinsaid non-actinic covering, and photographlng said copy by a secondexposure of the same plate through a half-tone screen.

2. The improvement in the art of photoengraving which consists ineliminating half-tone dots from predetermined portions of a half-tonenegative by covering the surface of the copy to be photographed with atransparent material. tracing on said cover overportions of said copyfrom which all half-tone dots are to be eliminated from the negativewith a pigment having high actinic value, inserting a backing of a colorhaving non-actinic value between said copy and said cover.photographing. said tracin on a sensitized plate, removing said backlng,and photographing said copy by a second exposure of the same platethrough a halftoned screen.

3. The improvement in the art of photoengraving which consists ineliminating half-tone dots from predetermined portions of a half-tonenegative by covering the surface of the copy to be photographed with atransparent material, tracing on said cover with a pigment over certainportions of said copy, inserting an opaque backing sheet between saidcopy and said cover, photographing said tracing on a sensitized plate,removing both backing and cover, and photographing said copy by a secondexposure of the same plate through a half-tone screen, saidbackingpreventing the photographing of the copy during said firstexposure.

HARRY J. VAN VALKENBURG.

